Digital pulse width modulators (DPWM) are used to generate a pulse width modulation (PWM) signal for creating a DC output in DC-DC converters. The duty cycle (percentage of time high) of the PWM signal is used to set the DC output voltage.
The PWM signal is sent to external switches that send an input voltage into an LC circuit, which includes an inductor and an output capacitor, to produce the output voltage. The output voltage is used to create a feedback signal. The feedback signal is used to adjust the PWM signal so as to keep the output voltage at the desired DC output voltage value.
Digital controllers for DC-DC converters usually regulate the output voltage by taking the samples produced by an analog-to-digital converter (ADC). To improve the converter efficiency, minimize the power consumption of the controller circuit and reduce the hardware complexity, the ADC and accompanying digital pulse-width modulator usually updates their values once per switching cycle. Previously, several such low-power, high-frequency digital controller IC implementations were presented. However, compared to analog IC controllers, the dynamic response of those is usually inferior, negatively affecting the size of the power stage components, especially the output capacitor.
Recent linear and non-linear digital controllers have demonstrated that oversampling of the output voltage results in significant response improvements and reduction of power stage components. However, such solutions usually introduce significant switching losses. As a result, for frequent load changes, the converter efficiency is lower compared to conventional implementations.